People who are born blind or become blind early in life often have sharper hearing, especially when it comes to musical abilities and tracking moving objects in space.
In separate studies – one published in the Journal of Neuroscience, the other in the Proceedings of the National Academy of Sciences – researchers from the University of Washington (UW) used functional magnetic resonance imaging (fMRI) to identify two differences in the brains of blind individuals that might be responsible for their abilities to make better use of auditory information.
The researchers found that in the auditory cortex, individuals who are blind showed narrower neural ‘tuning’ in discerning small differences in sound frequency than sighted subjects. They claimed this to be the first study to show that blindness results in plasticity in the auditory cortex and an “elegant example” of how infant brain development is influenced by the environment.
The second study examined how the brains of people who are born blind or become blind early in life represent moving objects in space. The research team showed that an area of the brain called the hMT+, which in sighted individuals is responsible for tracking moving visual objects, shows neural responses that reflect both the motion and the frequency of auditory signals in blind individuals. This suggests that in blind people, area hMT+ is recruited to play an analogous role – tracking moving auditory objects, such as cars or the footsteps of the people around them.